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Providing adequate green cover in the form of trees, parks and gardens is a nature-based solution which every city must adopt to address the urbanization and its impacts, as it helps to reduce the temperature, maintain the ecology and biodiversity, provide recreational facilities for the city inhabitants and many more. Accurate mapping and monitoring of Urban Green Spaces (UGS) through satellite images is essential to check whether a city has adequate green cover or not. Studies on UGS have mostly used Landsat and Sentinel-2A satellite images for extracting the green covered areas in cities. Though it is advantageous to use these freely available images, however the accuracy of extraction is a major concern as the images are of >10m spatial resolution. Distinguishing the various green cover types, such as trees, shrubs, cropland, etc. is not an easy task in low and medium resolution satellite images. To overcome these drawbacks, one has to use high (1-10m) and very-high resolution (<1m) images for extracting the UGS accurately, however, purchasing such 'cm' resolution satellite images is a costly affair. In order to balance between the cost and resolution, the best and viable option is to use the Google earth (GE) imagery and the same was attempted in the present study by proposing a simple threshold-based approach to extract the UGS and its types from GE imagery. To illustrate the proposed method, 15 sites from the city of Vellore, India were taken and the latest cloud free GE imagery was then downloaded, projected and carefully checked for its range of pixel values in different types of UGS classes. The threshold values of each UGS type were then used to reclassify the original GE image and finally the accuracy assessment was performed on the reclassified UGS map. The results were promising as the overall accuracy (OA) was > 90% at 12 sites and only 3 out of 15 sites exhibits OA in the range of 75-86%. In order to assess the performance of the proposed approach at other locations, 5 cities across the globe [2 from India (Bangalore and Hyderabad) and 3 from abroad (Barcelona, Kuala Lumpur, New York)] were taken and the results revealed that the proposed method performs well in extracting the UGS and its types as the OA was found to be above 90% at all the 5 cities. The proposed approach can be used by civic authorities not only to check whether the city has adequate green cover or not but also can monitor whether UGS has increased or decreased over the years using the historical GE images. [ABSTRACT FROM AUTHOR]

It is imperative to have a practical indicator for assessing the potential for phosphorus movement from soil to surface waters causing environmental pollution. The present study was undertaken with two groups of acidic soils from the terai and red and laterite agro-climatic zone of eastern India to estimate their phosphorus threshold values and establish a simple model with the clay content as the principal variable. The mean phosphorus adsorption maximum and phosphorus buffering capacity were higher in lateritic than terai soil. The change-point soil test values at which water soluble phosphorus enhanced abruptly ranged from 32 to 68 mg kg−1 and 28 to 63 mg kg−1 with Bray-1 and Mehlich-1 method, respectively, for the soils of the terai zone. Similarly, it varied from 47 to 90 mg kg−1 and 44 to 89 mg kg−1, respectively, for the lateritic soils. Application of phosphatic fertilizers should not be allowed beyond the threshold level, which was considered 75% of the change-point soil test value to avoid the risk of the soil becoming a source of phosphorus pollution for surface water bodies. The simplified models of phosphorus threshold level (mg kg−1) developed with either of the extractants were "4.75 × clay content (%) – 30" and "6.00 × clay content (%) – 75" for terai and lateritic soil, respectively. These models can be extended to the soils with similar mineralogy but varying in clay content for sustainable phosphorus management without limiting crop production. [ABSTRACT FROM AUTHOR]

Nickel is an essential micronutrient for leguminous plants. It has a large range between limiting and toxic levels. A pot experiment was conducted on two dominant soil series of Jharkhand i.e., Upland [Sidhamantoli (ST-5)] and Lowland [Tetratoli (TT-5)]. Five application levels of Ni, viz. 0.0, 2.5, 5.0, 10.0 and 20.0 mg kg−1 with pea (Pisum sativum L.) as test crop were arranged in three blocks in a glass house. An increasing trend of pea dry matter was observed with increasing Ni application level up to 10.0 mg kg−1. Nickel content in pea plant over control was found 1.36 to 2.53 folds higher with Ni application 2.5 to 20.0 mg kg−1. Accumulation of Ni in soil of Sidhamantoli series (upland situation) was noticed 1.11–4.29 mg kg−1 in top and 1.31–5.68 mg kg−1 in bottom of the pot, while in Tetratoli soil series (low land situation) Ni content was found 1.40–5.35 mg kg−1 in top and 1.25–4.95 mg kg−1 in bottom soil. Nickel application stimulates Plant growth parameters and that gradually increased with increasing Ni application levels up to 5.0 mg kg−1 in Sidhamantoli and up to 10.0 mg kg−1 in Tetratoli soil series, while at 20 mg kg−1 Ni application in both soil conditions showed negative effect. So, appropriate precaution should be maintained in application of Ni in leguminous plants and fixed a threshold value of Ni application level 5.0 mg kg−1 in upland Sidhamantoli (ST-5) and 10.0 mg kg−1 in low land Tetratoli (TT-5) soil series of Jharkhand plateau. [ABSTRACT FROM AUTHOR]

Background: Chest computed tomography (CT) imaging provides results more rapidly and with higher sensitivity than reverse transcription polymerase chain reaction in diagnosis of COVID-19., Aim: To evaluate diagnostic efficacy of chest CT imaging in diagnosis of COVID-19 cases based on age and duration of symptoms., Materials and Methods: A retrospective study conducted during December 2020 to June 2021 in a tertiary care hospital, India. Total 495 patients with typical clinical symptoms of COVID-19, reverse transcription polymerase chain reaction positive for COVID-19 and had undergone chest CT imaging were included. Descriptive statistical analysis was performed for all the variables. Receiver operating characteristic curve analysis was used to determine threshold value of chest CT severity score (CT&#95;SS) based on duration of symptoms and age to diagnose COVID-19., Results: Mean age of patients was 61.86 ± 10.77 years and 367 (71.4%) patients were male. Ground glass opacities were observed in 456 (92.1%) patients and in 332 (67.1%) patients, multilobes were affected. Total CT&#95;SS showed positive correlation with age (r = 0.257) and duration of symptoms (r = 0.625). Total CT&#95;SS >6 after a duration of 2 days of symptoms identified COVID-19 cases with sensitivity 90.8% (95% confidence interval [CI]: 87.5%-93.5%) and specificity 84.6% (95% CI: 76.2%-90.9%). Total CT&#95;SS >11 in patients aged more than 60 years identified COVID-19 cases with sensitivity 47.4% (95% CI: 41.2%-53.6%) and specificity 87.3% (95% CI: 82.3%-91.4%)., Conclusion: Threshold value of CT&#95;SS determined will help to expedite diagnosis of COVID-19 patients by the clinicians in an early stage especially in India and other developing countries which have a high patient volume and limited health resources., Competing Interests: None

Various source materials such as crude oil, automobile exhaust, coal, and wood combustion products were analyzed for polycyclic aromatic hydrocarbons (PAHs) and hopanes. Hopanes were detected in coal combustion-derived soot, along with petrogenic sources. Based on the correlation between the alkylated PAHs/parental PAHs ratio with their respective C30 hopane/PAHs ratio in these source materials, the criteria for differentiating the petrogenic and pyrogenic sources of PAHs were established. This study concluded that sediments contained exclusively pyrogenic PAHs when the following conditions were met: MP/P (methylphenanthrenes to phenanthrene) = 0.5, MPy/Py [(methylpyrenes + methylfluoranthenes) to (pyrene + fluoranthene)] = 0.15, and MC/C [(methylchrysenes + methylbenz[a]anthracenes) to (chrysene + benz[a]anthracene)] = 0.2. By contrast, the sediments contained exclusively petrogenic PAHs when the ratios of MP/P, MPy/Py, MC/C, and methyl PAHs (MPAHs)/PAHs exceeded 3.5, 1.5, 2.0, and 2.2, respectively. Based on these criteria, an intensive source apportionment of PAHs to sediments from three Indian metro cities, Chennai (n = 6), Mumbai (n = 6) and Kolkata (n = 12) (2003–2007), was determined. This investigation found that sedimentary PAHs from India were depleted in alkylated PAHs with low MP/P ≈ 0.7, MPy/Py ≈ 0.14, and MC/C ≈ 0.3, which contrasted with other tropical Asian countries, where elevated values of these ratios were detected. Among the three cities, Kolkata waters were more strongly influenced by pyrogenic sources of PAHs with very low alkylated PAHs ratios than Chennai and Mumbai sediments. The compositional differences were attributed to the dominant coal and biomass in Kolkata compared to the dominant usage of petrogenic cooking fuel (e.g., kerosene) and automobile-derived sources in Chennai and Mumbai. [ABSTRACT FROM AUTHOR]

The reserves of various forms of potassium (K), the threshold values for release of intermediate K, and the quantity/intensity (Q/I) parameters were studied in an Entisol, an Inceptisol and two Alfisols of West Bengal, India. The laboratory experiments were supplemented by a pot-culture experiment in absence of K fertilizer. The purpose was to study the release pattern of K in a rice-rice-rice cropping sequence. The results indicated that the Entisol and Inceptisol contained a higher amount of easily extractable non-exchangeable K, i.e. step-K. This was related to the dominance of micaceous minerals in clay fraction. The step-K content decreased in all the soils on subjecting them to repeated cropping. The Alfisols suffered a higher percentage decline in step-K than the Entisol and Inceptisol as observed after a sequence of three crops. The threshold values for release of intermediate K, showed a decrease in the Entisol and Alfisol studied after the third crop as compared to the first one. This was related to rather low diffusion coefficient of K for its mobility in the interlayer region. The Q/I parameters were favorable for crop growth in the Entisol examined and decreased in all the soils in course of repeated cropping. [ABSTRACT FROM AUTHOR]

Natural background levels (NBLs) and threshold values (TVs) are crucial parameters for identification and the quantification of groundwater pollution, and the evaluation of pollution control measures. The cumulative probability distribution technique was used for the evaluation of NBLs for 36 samples collected during two climate conditions in the part of the desert area from Rajasthan, India. The NBLs for Na+, Cl−, SO 4 2−, HCO 3 − , NO 3 − and F− ions were assessed and compared with the natural and anthropogenic processes. The TVs were also calculated for Na+, Cl−, SO 4 2−, HCO 3 − , NO 3 − and F− ions, and compared with the drinking limits of the Bureau of Indian Standards. Additionally, the pollution percentage (%) at the individual well was estimated and identified the polluted zones. Results indicate that most of the polluted areas were situated in the southern part, which was influenced by the natural and anthropogenic factors. The sodium concentrations above the TVs, in indicating the saline nature of water. Chloride threshold value above the drinking water limit was mainly observed in the dry season, related to intensive evaporation and industrial waste, which leads to groundwater quality degradation. The NO 3 − concentration (∼56% samples) above the TVs indicates extensive use of nitrate fertilizers and sewage effluent. The values of total dissolved solids (TDS) shows the suspicious scenario as about 84% of the samples in the dry period and about 89% in the wet season exceeding the drinking limit. Assessment of background concentrations and threshold values on regional and local scale assigns the basis for the identification of groundwater pollution, and helpful for better water quality guidelines to protecting of water resources. Image 1 • Cumulative probability plots have separated the natural background levels (NBLs). • Threshold values of hydrochemical parameters indicate the contamination. • Use of fertilizers and sewage effluent influence the NBLs of NO 3 − in groundwater. • Long-term dissolution of quaternary sediment and rocks causes high NBLs of HCO 3 −. • Evaporation of lowlands leads anomalous to salt concentration in groundwater. [ABSTRACT FROM AUTHOR]